This project's long-term goal is to investigate the role of growth factors (GFs) and their receptors in normal urothelial homeostasis and in the induction and maintenance of urothelial malignancy. This would entail: (1)\examining GF receptors on normal and malignant transitional epithelium; (2)\detecting and characterizing GFs produced by human TCC (TCC-GFs); and (3)\assessing effects of TCC-GFs and other GFs on normal and malignant urothelium and selected other cells. Initial work will be performed in vitro. Direct and competitive binding assays with radioisotope-labeled ligands will be used to detect and quantitate receptors for epidermal growth factor (EGF) on malignant and normal transitional epithelial cells, as well as to study their binding kinetics.To examine the receptors on fresh urothelium and correlate their distribution on TCC with tumor stage, grade, and prognosis, autoradiography will be utilized. Factor production will be documented by detecting growth-stimulating activity in the culture supernates from TCC cell lines growing in serum-free medium on the producing and/or other TCC cells. Following preliminary sizing, growth-stimulating fractions will be further purified. Selected chemical and physical properties, once characterized, will be compared with other described GFs including EGF. Active frac-tions will be tested for their ability to stimulate growth of normal fibroblasts and urothelium in soft agar as an indication of transforming ability. Assessment of response to GFs will includemonitoring in vitro growth, transformation, DNA synthesis, induction of ornithine decarboxylase activity, and light and electron microscopic morphologic alterations of nonmalignant and malignantcells. The bladder's epithelium is in the unique position of being perpetually bathed by pools of naturally occurring mitogens such as EGF, which are excreted in the urine in very high concentrations in biologically active forms. The continuous exposure of urothelial cells to such substances (including those which target cells produce) may result in continuous stimulation, continuous celldivision, and eventual loss of growth control (i.e., transformation). Thus, it is quite likely that the study of tumor and normal GFs will help elucidate the processes which induce and maintainTCC. Clinical applications await the preliminary studies outlined above but include clarificationof the variable malignant behavior of TCC and provision of markers of malignancy and new approaches to staging, treatment, and prevention of TCC. (J)